Mailing devices of this general type are known. The simplest and best known form may be an airmail letter which has gummed edges and can be folded together to form its own envelope. Other devices are known (see for example British Patent Specification No. 1,555,140) where information is printed or typed on one side of the paper only, and where the recipient's address appears through a window once the paper has been folded.
U.S. patent specification No. 2,340,700 (Sawdon) discloses a multiform envelope having four main sections and including a return envelope. Information is printed on this device in at least two diagonally opposite sections before folding it to form an envelope. The device is not suitable for printing by a mechanized device such as a computer printer, and is not suitable for use in the form of "continuous stationery," as used in mechanized printers.
U.S. patent specification No. 4,055,294 (Traise) discloses a combined mailer and return envelope assembly which is in the form of a continuous web, with adjacent assemblies along the length of the web joined to one another by rows of perforations. Web feed holes are provided at the web margins so that the assemblies can be fed through a computer printer. This assembly has a relatively small area for bearing printed matter for the information of the addressee, and is a very complicated construction.